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Component Function and Operating Environment

The brake disc is a very critical part of any vehicle let alone the Aston Martin. Manufacturing Processes It is a type of brake that makes use of calipers to bring pairs of pads to rub against a disc in order to create friction. This is either done to reduce the speed of the shaft such as a vehicle axe or to hold it at a position. Mostly made out of cast iron

brake discs are usually used for vehicles but can be practically applied to any rotating shaft. Although the exact constitution varies from machine to machine, there are three basic components of a brake disc including the rotor, calipers and brake pads. The purpose of the rotor is to continue rotation with the road wheel. Manufacturing Processes  Once there is a need to stop, the rotor can act as a smooth surface against which the pads come into action. The brake disc pads are basically present to convert the hydraulic force of the caliper into a frictional force that is exerted against the disc

The caliper is in charge of the pistons that put the pads into contact with the disc. Another important component of the brake disc is the proportionate valves. These valves manage the work load on the brake by dividing the effort required and distributing it proportionally to front and rear wheels. The materials used inside brake discs are basically those having high friction coefficients. The choice may vary from machine to machine based on individual preferences but the thing to note is that the material should be able to absorb high levels of heat without affecting the performance adversely.

Brake disc and its Role in the Machine
With production started in the late 1890s, the brake disc has become a very important component of modern vehicles. Over time the device has gone through the process of evolution as technicians from different periods of time have made improvements to the concept. The modern brake disc is connected to the wheel or the axle. There have been plenty of reports from the past where the failure of the brake disc has led to damage to other components as well. However modern brake discs use mechanic, hydraulic, pneumatic and electromagnetic mechanisms to bring the rotations shaft to a halt.

Working conditions of the Brake Disc
Since the brake disc makes use of friction to bring the wheel to stoppage, a lot of heat energy is produced. Brake fade is a phenomenon that is refers to a state where an excess of heat energy makes the brakes more prone to damage and increases chances of failure. However modern brake discs including those used in Aston Martin are designed to be readily cooled. Compared to drum brakes, brake discs offer better performance because of this feature. Not only do they absorb large atmospheric pressure and temperatures, they can also recover quickly from immersion i.e. a state of being wet that makes functioning difficult. Disc brakes are also found to be capable of supporting high temperatures up to 900 degree Celsius. Any temperatures above this can cause heat shocks leading to brake fade, although improvements are currently being sought.

Material Properties and Selection
There are a few factors that need to be kept in mind before the selection of the right material for the disc barking system. The chosen material should firstly be good at dissipation of heat. One of the problems with the disc braking system is the heating up of the brake pads and the disc rotor. It can affect the efficiency of the system and in some extreme cases can stop functioning altogether, making it one of the major concerns that the manufacturer has to address while selecting the material for the disc brake. Secondly, the material should also be adequately soft which reduces the metal to metal wear. This increases the life of the disc and the pads making it economical for the consumer.

It is also related to the accumulation of heat. Harder material heats up easily and cools down slowly. But the material should only be soft enough so that it can withstand the pressure. It also reduces the friction dust which makes the cleaning of the brake pads a lot easier. Lastly, the material should not be noisy because it can be disturbing. Some pads start producing noise when they are either severely used or when their replacement time is near. The next section suggests the materials which have been used over the passage of time and their relative suitability in serving all four purposes which are

mentioned above.

Suitable materials and their efficacy
Historically there are four famous types of materials which have been used for making the disc brakes and the braking pads especially in the automotive sector. It is crucial that the material qualifies against all the requirements which are mentioned in the previous section. Before 1970, asbestos based material was used to produce the braking material. The material scored good on all the other requirements except the brake dust which was the unhealthy byproduct causing serious health issues if ingested. The manufacturers hence had to come up with new material which had same friction coefficient and could easily be molded and shaped.

Hence the non-asbestos linings were introduced as direct replacements which were made of organic fibers, which were bonded by pressure and held together by glue. These linings also had a small amount of metal such as brass, no more than 10 to 20 percent, to make the dissipation of heat more efficient and making them abrasive. The second type was the semi metallic linings which had more metallic content in them, increased to around more than 50 percent and the organic content was hence reduced. The metal increased the hardness of the system making the heat dissipation a lot more efficient. Due to increase in friction coefficient,

the braking power was also increased reducing the stopping time. Despite this, the dust content was not increased rather it was reduced. But the increase in abrasiveness due to metal also increased the generation of heat by the material. The hardness also reduced the longevity of the system because the pads had a lesser time span now. Noise was another issue due to which the manufacturers knew that there is still room for improvement. Hence, in late eighties, they came up with ceramic based frictional material. It comprises of two main ingredients:
1. Copper- It is softer hence reducing the wear and tear without compromising the heat dissipation.
2. Space-age technology fibrous ceramic- It provides rigidity without increasing the problems…